import java.util.Scanner;

public class s {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        char[] ch = new char[100];
        int[]count=new int[266];
        String string=scanner.nextLine();
        for (int i = 0; i < ch.length; i++) {
            count[string.charAt(i)]++;
            if (string.charAt(i)==1){
                System.out.println(string.charAt(i));
            }
        }
    }
}